Rule systems
Building rules with Hob
Ask for a mechanic in plain words: what Hob builds, how it borrows from the presets, testing on the bench, and undoing.
Say what you want
Hob, the Studio's assistant, can read and change your world's rule system. Describe a mechanic in plain words and Hob builds it as working rules: conditions, pools, tracks, rule cards, whole systems. It then tells you what it made as the cards' sentences. Everything it changes is checked by the same validation as the Rules tab, and saved straight away.
Hob builds mechanics in the rules, not as lore. A curse with a price, a blessing, a reputation, a hunger, a ship: each becomes a condition on the conditions list, a pool for the storyteller if it needs one, a kind of thing if it's owned, and the rule cards that tie them together, in one change.
What Hob can do
- Read the rules
- Your world's system, whole or one piece ("the bands of the ability check"), or the native engine if it has none.
- Read a preset
- Any of the six presets, whole or one piece, without touching your world: to see how Forged writes stress, or how Hope and Fear compares its dice.
- Switch to a preset
- A fresh copy of a preset, or back to the native engine. Your own changes to the old system go.
- Make a system from scratch
- The same as the composer: an engine, dice (mixed if you like), stats with what they cover, skills, tracks, outcome names. Hob fills in the spec from your description.
- Change anything
- Rename a stat, add a skill or a track, change a check's trigger, reword a band's guidance, add a condition, a pool, a kind of thing, a rule card, an enemy template, the level table, a formula.
- Spells, abilities, creatures
- Write an ability or a creature in the system's own terms, or search the library (Classic d20: the SRD 5.1's 316 spells and 334 monsters) and add entries from it, already checked.
- Peoples
- Map one of your world's peoples to the rules' templates ("the Ashling are like high elves, with fire resistance"), write a template of its own, or a trait it needs. See Peoples under your rules.
Each change goes through as a whole: all of a request's changes apply together, or none do. If the rules wouldn't hold (a formula naming a stat that doesn't exist, a card naming a track you removed), Hob is told why in words, fixes it and tries again.
Borrowing from a preset
When you name or describe something a preset already does well, Hob reads how that preset writes it first, and builds from that instead of inventing its own version. It can copy a piece outright (a track, a condition list, a pool, a set of cards), then rename and adjust it.
{ "op": "add", "path": ["tracks"],
"value": { "fromPreset": { "preset": "forged", "part": ["tracks", "stress"] } } }Copying keeps what makes the preset's version work, down to the details: Forged's Stress clears itself when a Trauma lands, and the death-save cards reset their clocks. A copy is yours; the preset never changes it.
Adding from the library
A Classic d20 world (or a copy of it) has the SRD 5.1 to add from. Hob searches it by words and level, then adds the entries you want as they are, in one change. Each is a copy: change it afterwards like anything else.
{ "op": "add", "path": ["bestiary"],
"value": { "fromLibrary": { "kind": "bestiary", "id": "owlbear" } } }Requests that work well
| Ask | Hob builds something like |
|---|---|
| “A crit should give Inspiration.” | When a roll is a critical → Inspiration +1. |
| “The Witchwood makes everything harder.” | Before any roll in the Witchwood → disadvantage. |
| “Poison should hurt every turn until cured.” | A Poisoned condition (counts down never), and: Each turn (while Poisoned) → Hit points −1. |
| “Fame: every four foes beaten, they get known in the capital.” | When they defeat a foe → tick Renown 1. / When the Renown clock fills → +100 xp; Known in the capital. |
| “A ward that stops the first big hit each fight.” | A Warded condition, a card putting it on when a fight starts, and: Before damage is taken (while Warded) → blocked: The ward takes the blow; lose Warded. |
| “Ships with hull and crew; ramming hurts both.” | A Ship kind of thing (hull, crew) and the cards that mark them. |
| “A grim river game where every crossing costs your nerve.” | A system from scratch: stats for the river, a Nerve track, and cards that spend it. |
| “A blood strike: 2 Blood Oath for a harder blow, and the debt grows.” | An ability: costs 2 Blood Oath, rolls the system's check, on a success 1d8 damage and Blood Debt +1. |
| “A frost troll that only fire keeps down.” | A creature on the Troll's numbers: regenerates 10 unless fire struck it, immune to cold. |
- Say what it should do in play, not how to build it: “bosses should be scarier from tier 3” is enough.
- Name the moment: when it happens (a roll, a rest, a place, a fight), and what changes.
- Name the source if a preset already has it: “like Forged's stress”, “fifth-edition death saves”.
- Check the sentences Hob reports. If one reads wrong, say what you meant; they are exactly what runs.
Test it on the bench
After a change, press Try it at the top of the Rules tab and type something a character would do. The bench runs it through the same rules judge as play, on a starting character, and shows which check and words were picked, one real roll, and how a thousand rolls of it would land. It runs your unsaved edits too, so you can compare before and after.
Things worth checking: a starting character should pass an ordinary Standard check more often than not; Hard should feel hard; a critical should be rare enough to be exciting. The odds tables in Making your own system are a guide.
Undo
Hob's rule changes save at once, so a reply that changed the rules can be undone from Hob's panel: the system goes back to exactly what it was before that reply. A system replaced with the composer's Start again from scratch can't be undone that way.